This invention relates to a rewritable medium recording apparatus which can handle a card having a thermally reversible color developing layer.
Recently, there have been widely spread rewritable medium recording apparatuses of the type having, in addition to the function of recording and reproducing magnetic information by means of a magnetic head, a rewrite function by which the information printed can be rewritten over and over by means of a thermal head and an erase head, in order to handle a card having a thermally reversible color developing layer on which the information is visible as characters. The card system comprising the combination of such card and rewritable medium recording apparatus can be applied to a broad field including the point card system for shopping center, card system for staff's cafeteria and card system for the rental business, by making use of the characteristic that the information is visible.
A summary of thermally reversible color developing layer of such card will be described with reference to FIG. 9 which is a plan view of a card having a thermally reversible color developing layer and FIG. 10 which is a characteristic diagram showing the color developing/erasing characteristics of the thermally reversible color developing layer.
In FIG. 9, a card 1 has a thermally reversible color developing layer formed on the entire silver base, and is printed except in a printable printing area 1a. Since the printing area 1a is normally transparent, it appears silver which is the color of the base, but when it is heated at a predetermined temperature, heated portions turn white so that white characters appear on the silver background. The card 1 is formed on the back thereof, opposite to the printing area 1a, with a recording layer on which information can be recorded by making use of the magnetism.
The thermally reversible color developing layer is summarized as follows. As shown in FIG. 10, distributed in the thermally reversible color developing layer is a low-molecular substance having the property that the crystal structure thereof is changed when receiving the thermal energy. In the condition shown at a point A, since the crystal structure of the low-molecular substance is in the large single crystal state, the light is allowed to transmit so that the thermally reversible color developing layer appears to be transparent. On the other hand, in the condition shown at a point B, the crystal structure is in the polycrystal state, and therefore the light is scattered to cause the thermally reversible color developing layer to become opaque, with the result that the thermally reversible color developing layer appears white.
Explaining this phenomenon in connection with the color developing/erasing characteristics, if a card in the transparent condition shown at the point A is heated, it starts to become opaque at temperatures 90 to 100.degree. C. and, If cooled down to room temperature from this condition, it is turned into the completely opaque condition as shown at the point B. On the other hand, if the card in the opaque condition shown at the point B is heated, it is turned into the transparent condition at temperatures around 80.degree. C., and therefore it is possible to reversibly perform the color developing/erasing process by repeated change in condition between transparent and opaque.
Now, the structure of a conventional rewritable medium recording apparatus will be described. FIG. 11 is a schematic view showing the structure of the conventional rewritable medium recording apparatus, and FIG. 12 is a plan view of a card used for the conventional rewritable medium recording apparatus.
In FIGS. 11 to 12, a rewritable medium recording apparatus 2 comprises a recording head 3 by which at least one of recording and reproduction of information on a recording layer of a card 1 is performed by making use of magnetism, a printing unit 5 having a print head 4 by which information is printed on a thermally reversible color developing layer of the card 1, and an erasing unit 7 having an erase head 6 by which the information printed on the thermally reversible color developing layer is erased. The card 1 used for the rewritable medium recording apparatus 2 has a thermally reversible color developing layer on one surface and a recording layer on the other on which information can be recorded, reproduced and erased by means of the recording head 3. By heating a printing area 1a on the thermally reversible color developing layer by means of the print head 4, characters are printed white to become visible.
The card 1 is inserted in a slot 8 of the printing unit 5 with its printing area 1a facing up and caused to reciprocate twice by means of feed rollers 9 to 11 driven by drive means (not shown), during which all process is completed.
In the first reciprocation, at least one of recording and reproduction of information on the recording layer on the back of the card 1 is performed by means of the recording head 3, while the card 1 is conveyed forward by the feed rollers 9 to 10. Then, the card 1 is fed into the erasing unit 7 by the feed rollers 11 for the purpose of erasing the information printed. When the card 1 is brought to a stop in the erasing unit 7, a table 13 adapted to be moved up and down by a solenoid 12 is moved upward until the printing area 1a of the card 1 is pressed against the erase head 6 heated to a temperature around 80.degree. C., thereby erasing the information printed. In this case, the whole printing area 1a of the card 1 is subjected to erasing because the width of the printing area 1a in the longitudinal direction of the card 1 coincides with the width of the erase head 6. After the above process is completed, the feed rollers 11 are rotated reversely so that the card 1 is fed back into the printing unit 5 again to make ready for the printing process.
In the second reciprocation, character information is written in turn on the printing area 1a on the front of the card 1 by means of the print head 4 in the printing unit 5. The print head 4 is enabled to move up and down when being driven by a solenoid 14. When the card 1 is on the platen roller 15, the print head 4 is lowered to be pressed against the printing area 1a and then a large number of heating resistance elements of the print head 4 are heated to a temperature around 100.degree. C. according to the print pattern, thereby printing optional characters, figures and the like on the printing area 1a of the card 1. After the above process is completed, the card 1 is conveyed by the feed rollers 9 to 10 so as to be caused to pass over the recording head 3. While the feed rollers 9 to 10 are rotated reversely to cause the card 1 to pass over the recording head 3, the information recorded is verified. Thereafter, the card 1 is released out of the slot 8.
However, in the conventional rewritable medium recording apparatus described above, when erasing the information printed on the card 1 in the erasing unit 7, the printing area 1a of the card 1 shown in FIG. 12 is subjected to erasing over a wide range all at once by means of the stamp type erase head 6. This inevitably causes the erasing unit 7 to be increased in size, and therefore it has been necessary to provide the erasing unit 7 separately from the printing unit 5. Further, since the card 1 fed into the erasing unit 7 must be fed back into the printing unit 5 after the erasing process, the card 1 should undergo the erasing process while being held between the feed rollers 11. For this reason, since it is necessary For the card 1 to reserve a space for holding, a considerably wide area is occupied by unusable portion, giving rise to a problem that the printing area 1a that can be set on the card 1 (in FIG. 12, approx. 40 mm long in the longitudinal direction of the card 1) should inevitably be narrowed.